Project Summary/Abstract The goal of this research proposal is to identify patients with multiple myeloma at high-risk of developing venous thromboembolism through derivation and validation of a clinical risk prediction model. The clinical utility and risk-benefit ratio of the model will be assessed with decision analysis and will aid in determining the role of the model in clinical practice. Three aims will address the overall hypothesis that a multiple myeloma-specific clinical risk prediction model will be able to accurately identify patients at highest risk of developing venous thromboembolism and thereby guide selection for use of primary thromboprophylaxis. Ultimately, this will reduce the burden of venous thromboembolism in multiple myeloma and improve outcomes while balancing a risk-benefit ratio. The three aims that comprise this proposal include; Aim 1: To develop a risk prediction model for venous thromboembolism in multiple myeloma using a nationwide cohort of patients, Aim 2: To prospectively validate the risk prediction model and determine the impact of D-dimer on model discrimination, Aim 3: To quantify the risks and benefits of thromboprophylaxis on quality-adjusted survival in multiple myeloma using decision analysis. To complete these Aims, Kristen Sanfilippo MD, MPHS will receive training in the application of clinical prediction models, Bayesian statistics and decision analysis through dedicated coursework and guidance under the supervision of the primary mentor, Brian Gage MD, MSc, and secondary mentor, Kenneth Carson MD, PhD. In addition, the success of the proposal will be supported with collaborations from Jeff Gill PhD, David Calverley MD, and Gary Lyman MD, MPH. This project is in direct line with strategic goal 2 of the National Heart Lung and Blood Institute, as this clinical investigation will serve to advance the prediction and prevention of venous thromboembolism.